1. Field of the Invention
The present invention relates to a combustion apparatus applied to boilers for thermal power plants or chemical plants, or furnaces and the like for the chemical industry.
2. Description of Related Art
FIG. 14 is a horizontal sectional view showing a conventional boiler furnace using a rotational combustion system and the concept of a combustion flame in the furnace.
As shown in the figure, a square furnace 1 is provided with burners 6 for injecting fuel at four corners 10.
FIG. 15 shows another furnace 1 of the prior art. Unlike the furnace shown in FIG. 14, the furnace 1 is provided with burners 6 at two places on the furnace front wall 2 and at two places on the furnace rear wall 3, not at the furnace corners 10. In this case, the burners 6 are not disposed on the right and left side walls 4 and 5 of the furnace. Other configurations are the same as those shown in FIG. 14.
The furnace 1 shown in FIGS. 14 and 15 has an imaginary circle 7 having a fixed diameter, which is set in the furnace interior 1a. Also, in these figures, in-furnace injection direction axis lines 9 showing the direction of fuel and combustion air of burner are set so as to be tangent to the imaginary circle 7. The fuel and combustion air injected from the burner 6 into the furnace 1 are injected into a furnace interior 1aalong this axis line, thereby forming a rotational combustion flame 8.
In the prior art, in order to form a stable and high-performance rotational combustion flame, all the burners 6 are disposed at the furnace corners 10 as shown in FIG. 14, or they are disposed on the furnace walls opposed to each other, that is, on the furnace front wall 2 and the furnace rear wall 3 as shown in FIG. 15, or they are disposed on the furnace right side wall 4 and the furnace left side wall 5, and an appropriate diameter of the imaginary circle 7 is selected to obtain a stable rotational combustion flame.
FIG. 16 shows a furnace 21 for a boiler or the like. As shown in the figure, the furnace 21 is provided with burners 25 at four places on the furnace front wall 22 and at four places on the furnace rear wall 23. Of these burners 25, four burners 25 disposed on the right side in the figure are arranged so that the in-furnace injection direction axis line 28 showing the direction of the fuel and combustion air injected from the burner 25 is tangent to the circumference of an imaginary circle imagined in the furnace 21, having a fixed diameter, and four burners 25 disposed on the left side in the figure are also arranged likewise so that an imaginary circle 26 is set. The fuel and combustion air injected from the burner 25 are injected into a furnace interior 21a along the axis line 28 and burned, thereby forming a flame 27. In the furnace 21, therefore, two rotational combustion flame vortexes having a different center position are formed.
In the prior art, all of the burners 25 are disposed on a set of opposed furnace walls, the furnace front wall 22 and the furnace rear wall 23, and the diameter of the imaginary circle 26 is selected appropriately, whereby stable and proper rotational combustion flame vortexes 29 are formed.